Your task is to prevent the input of invalid data at line 25 of the program (input of the numeric grade). Input is considered valid if and only if

== Rules for Valid Input ==

It is an integer

It is greater or equal to 0 but less than or equal to 100

The requirements of the program are:

The program must only accept data the meets the rules for valid input above.

If invalid data is input you program should print the error message "invalid data" and exit

No additional features are to be added.

# This program inputs a user score in % and outputs a letter grade.

# scale used is

# 90 or greater is an A

# Less than 90 but 80 or greater is a B

# Less than 80 but 70 or greater is a C

# Less than 70 but 60 or greater is a D

# Less than 60 is an F

#

def convert_grade_to_letter(number_grade):

letter_grade = 'F'

if number_grade >= 90:

letter_grade = 'A'

elif number_grade >= 80:

letter_grade = 'B'

elif number_grade >= 70:

letter_grade = 'C'

elif number_grade >= 60:

letter_grade = 'D'

return letter_grade

def main():

number_grade = int(input("Input number grade: "))

letter_grade = convert_grade_to_letter(number_grade)

print("Letter grade: " + letter_grade)

main()